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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
351

Algorithms for wire length improvement of VLSI circuits with concern to critical paths / Algorítmos para redução do comprimento dos fios de circuitos VLSI considerando caminhos críticos

Hentschke, Renato Fernandes January 2007 (has links)
Esta tese objetiva propor algorítmos para a redução do tamanho dos fios em circuitos VLSI considerando elementos críticos dos circuitos. O problema é abordado em duas perspectivas diferentes: posicionamento e roteamento. Na abordagem de posicionamento, a tese explora métodos para realizar posicionamento de um tipo particular de circuito VLSI, que são conhecidos como circuitos 3D. Diferente de trabalhos anteriores, este tese aborda o problema considerando as conexões verticais (chamadas 3D-Vias) e as limitações impostas pelas mesmas. Foi realizado um fluxo completo, iniciando no tratamento de pinos de entrada e saída (E/S), posicionamento global, posicionamento detalhado e posicionamento das 3D-Vias. A primeira etapa espalha os pinos de E/S de maneira equilibrada objetivando auxiliar o posicionamento para obter uma quantidade reduzida de 3D-Vias. O mecanismo de posicionamento global baseado no algorítmo de Quadratic Placement considera informações da tecnologia e requerimento de espaçamento de 3D-Vias para reduzir o comprimento das conexões e equilibrar a distrubuição das células em 3D. Conexes críticas podem ser tratadas através da insercão de redes artificiais que auxiliam a evitar que 3D-Vias sejam usadas em conexões críticas do circuito. Finalmente, 3D-Vias são posicionadas por um algorítmo rápido baseado na legalizaçãao Tetris. O framework completo reforça os potenciais benefícios dos circuitos 3D para a melhora do comprimento das conexões e apresenta algorítmos eficientes projetados para circutos 3D podendo estes serem incorporados em novas ferramentas. Na abordagem de roteamento, um novo algorítmo para obtenção de árvores de Steiner chamado AMAZE é proposto, combinando métodos existentes com novos métodos que são efetivos para produzir fios curtos e de baixo atraso para elementos críticos. Um técnica de biasing atua na redução do tamanho dos fios, obtendo resultados próximos da solução ótima enquanto que dois fatores de timing chamados path-length factor e sharing factor propiciam melhora do atraso para conexões sabidas como críticas. Enquanto que AMAZE apresenta melhorias significativas em um algorítmo padrão na indústria de CAD (Maze Routers), ele produz árvores de roteamento com uso de CPU comparável com algorítmos heurísticos de árvore de Steiner e menor atraso. / This thesis targets the wire length improvement of VLSI circuits considering critical elements of a circuit. It considers the problem from two different perspectives: placement and routing. On placement, it explores methods to perform placement of 3D circuits considering issues related to vertical interconnects (3D-Vias). A complete flow, starting from the I/O pins handling, global placement, detailed placement and 3D-Via placement is presented. The I/O pins algorithm spreads the I/Os evenly and aids the placer to obtain a reduced number of 3D-Vias. The global placement engine based on Quadratic algorithm considers the technology information and 3D-Via pitch to reduce wire length and balance the cells distribution on 3D. Critical connections can be handled by insertion of artificial nets that lead to 3D-Via avoidance for those nets. Finally, 3D-Vias are placed by a fast algorithm based on Tetris legalization. The whole framework enforces the potential benefits of 3DCircuits on wire length improvement and demonstrates efficient algorithms designed for 3D placement that can be incorporated in new tools. On routing, a new flexible Steiner tree algorithm called AMAZE is proposed, combining existing and new methods that are very effective to produce short wire length and low delay to critical elements. A biasing technique provides close to optimal wire lengths while a path length factor and a sharing factor enables a very wide delay and wire length trade-off. While AMAZE presents significant improvements on a industry standard routing algorithm (Maze Routers), it produces routing trees with comparable speed and beter delay than heuristic Steiner tree algorithms such as AHHK and P-Trees.
352

Video-Based 3D Textures

Mustafa, Mohammad January 2007 (has links)
A new approach for object replacement in 3D space is presented. Introducing a technique that replaces the older two dimensional (2D) based facial replacement method performed by compositing artist in motion picture productions and video commercial industry. This method uses 4 digital video cameras filming an actor from 360 degrees, the cameras are placed with 90 degrees in between, the video footage acquired is then used to produce a 3D video texture consisting of video segments taken from different angles representing the object from 3D point of view. The video texture is then applied to a 3D modelled head matching the geometry of the original object. Offering the freedom of showing the object from any point of view from 3D space, which is not possible using the current two dimensional method where the actormust at all time face the camera. The method is described in details with images showing every stage of the process. Results are presented as still frames taken from the final video footage and as a video file demonstrating them.
353

Um estudo sobre a aplicabilidade da prototipagem 3D na gestão das cirurgias odontológicas / A study on the applicability of 3D prototyping in the management of dental surgeries

Castro, João Henrique Dayrell de 26 March 2018 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2018-04-27T13:04:57Z No. of bitstreams: 2 Dissertação - João Henrique Dayrell de Castro - 2018.pdf: 7299168 bytes, checksum: efabcdcc029c5f210c34a1d570717bbb (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-04-27T13:17:35Z (GMT) No. of bitstreams: 2 Dissertação - João Henrique Dayrell de Castro - 2018.pdf: 7299168 bytes, checksum: efabcdcc029c5f210c34a1d570717bbb (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-04-27T13:17:35Z (GMT). No. of bitstreams: 2 Dissertação - João Henrique Dayrell de Castro - 2018.pdf: 7299168 bytes, checksum: efabcdcc029c5f210c34a1d570717bbb (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-03-26 / Taking into consideration the different types of problems faced in the surgical procedures related to planning, this study presented a new possibility with the use of 3D prototyping, aiming to assist the dental professionals in the dental implant management and other procedures. This research evaluated the use of prototyping as an auxiliary tool for a safe surgical planning, considering that it provides the most faithful reproduction of the dental arches. The methodology evaluated the creation of prototypes using tomographic image les manipulated by InVesalius software, which processes 3D images for the generation of three dimensional objects to be printed by material extrusion. The objective was to create models to facilitate the management of surgical procedures in Implant Dentistry, with consequent minimization of errors and greater comfort for the patient. From images acquired in the public image bank www.dicomlibrary.com a three-dimensional model was created and printed. Following a dental implant procedure was performed on the printed model, following all step sof the procedure that s hould be done on the patient. As a result practical applicability will denote several possibilities, that increasingly digital technology nds and performs variables that in the past seemed impossible. Technological evolution implies an ever more complete future in relation to the diagnosis, planning and health are a treatment. / Levando em consideração os diversos tipos de problemas enfrentados nos procedimentos cirúrgicos, relacionados ao planejamento, neste estudo apresentou uma nova possibilidade com o uso da prototipagem 3D, objetivando auxiliar os trabalhos dos profissionais da área odontológica, no caso da gestão de implantes dentários e demais procedimentos. Essa pesquisa avaliou a utilização da prototipagem como ferramenta auxiliar para um planejamento cirúrgico seguro, considerando que esta, proporciona a reprodução mais fiel das arcadas dentárias. A metodologia avaliou a criação de protótipos utilizando arquivos de imagens tomográficas manipuladas pelo software InVesalius, que processa imagens 3D para geração de objetos tridimensionais a serem impressos por extrusão de material. O objetivo foi criar modelos para facilitar o gerenciamento dos procedimentos cirúrgicos em Implantodontia, com consequente minimização de erros e maior conforto para o paciente. A partir de imagens adquiridas no banco público de imagens www.dicomlibrary.com um modelo tridimensional foi criado e impresso. Na sequência um procedimento de implante dentário foi executado no modelo impresso, seguindo todos os passos do procedimento que deverá ser feito no paciente. Como consequente aplicabilidade prática denotará possibilidades diversas, que cada vez mais a tecnologia digital encontra e realiza variáveis que no passado parecia impossível. A evolução tecnológica implica num futuro cada vez mais completo com relação ao diagnóstico, planejamento e tratamento das áreas da saúde.
354

Algorithms for wire length improvement of VLSI circuits with concern to critical paths / Algorítmos para redução do comprimento dos fios de circuitos VLSI considerando caminhos críticos

Hentschke, Renato Fernandes January 2007 (has links)
Esta tese objetiva propor algorítmos para a redução do tamanho dos fios em circuitos VLSI considerando elementos críticos dos circuitos. O problema é abordado em duas perspectivas diferentes: posicionamento e roteamento. Na abordagem de posicionamento, a tese explora métodos para realizar posicionamento de um tipo particular de circuito VLSI, que são conhecidos como circuitos 3D. Diferente de trabalhos anteriores, este tese aborda o problema considerando as conexões verticais (chamadas 3D-Vias) e as limitações impostas pelas mesmas. Foi realizado um fluxo completo, iniciando no tratamento de pinos de entrada e saída (E/S), posicionamento global, posicionamento detalhado e posicionamento das 3D-Vias. A primeira etapa espalha os pinos de E/S de maneira equilibrada objetivando auxiliar o posicionamento para obter uma quantidade reduzida de 3D-Vias. O mecanismo de posicionamento global baseado no algorítmo de Quadratic Placement considera informações da tecnologia e requerimento de espaçamento de 3D-Vias para reduzir o comprimento das conexões e equilibrar a distrubuição das células em 3D. Conexes críticas podem ser tratadas através da insercão de redes artificiais que auxiliam a evitar que 3D-Vias sejam usadas em conexões críticas do circuito. Finalmente, 3D-Vias são posicionadas por um algorítmo rápido baseado na legalizaçãao Tetris. O framework completo reforça os potenciais benefícios dos circuitos 3D para a melhora do comprimento das conexões e apresenta algorítmos eficientes projetados para circutos 3D podendo estes serem incorporados em novas ferramentas. Na abordagem de roteamento, um novo algorítmo para obtenção de árvores de Steiner chamado AMAZE é proposto, combinando métodos existentes com novos métodos que são efetivos para produzir fios curtos e de baixo atraso para elementos críticos. Um técnica de biasing atua na redução do tamanho dos fios, obtendo resultados próximos da solução ótima enquanto que dois fatores de timing chamados path-length factor e sharing factor propiciam melhora do atraso para conexões sabidas como críticas. Enquanto que AMAZE apresenta melhorias significativas em um algorítmo padrão na indústria de CAD (Maze Routers), ele produz árvores de roteamento com uso de CPU comparável com algorítmos heurísticos de árvore de Steiner e menor atraso. / This thesis targets the wire length improvement of VLSI circuits considering critical elements of a circuit. It considers the problem from two different perspectives: placement and routing. On placement, it explores methods to perform placement of 3D circuits considering issues related to vertical interconnects (3D-Vias). A complete flow, starting from the I/O pins handling, global placement, detailed placement and 3D-Via placement is presented. The I/O pins algorithm spreads the I/Os evenly and aids the placer to obtain a reduced number of 3D-Vias. The global placement engine based on Quadratic algorithm considers the technology information and 3D-Via pitch to reduce wire length and balance the cells distribution on 3D. Critical connections can be handled by insertion of artificial nets that lead to 3D-Via avoidance for those nets. Finally, 3D-Vias are placed by a fast algorithm based on Tetris legalization. The whole framework enforces the potential benefits of 3DCircuits on wire length improvement and demonstrates efficient algorithms designed for 3D placement that can be incorporated in new tools. On routing, a new flexible Steiner tree algorithm called AMAZE is proposed, combining existing and new methods that are very effective to produce short wire length and low delay to critical elements. A biasing technique provides close to optimal wire lengths while a path length factor and a sharing factor enables a very wide delay and wire length trade-off. While AMAZE presents significant improvements on a industry standard routing algorithm (Maze Routers), it produces routing trees with comparable speed and beter delay than heuristic Steiner tree algorithms such as AHHK and P-Trees.
355

Otočný stolek k 3D skeneru / Rotary table for 3D scanner

Suchý, Lukáš January 2020 (has links)
This master thesis deals with the 3D scanning. This thesis explain methods of reversal engineering with a special aim for technical disciplines. Also some examples are being given. Next part deals with the 3D scanning technology and focuses on separation of scanners to a different groups and associated technology. Basically the scanning methods are separable to destructive and non-destructive groups. An images are obtained by 3D scan, its problematics and z-axis acquisition follow in next part of the thesis. Afterwards some key parameters suitable for selection of scanning systems are selected. A scanner "David SLS2" and its basic parameters, manipulation, service and calibrating process is being described. Last part deals with function and construction of rotating table used together with the 3D scanner David SLS2.
356

Návrh a realizace 3D tiskárny s podporou síťového tisku / Design and implementation of 3D printer with network printing support

Špringer, Radek January 2016 (has links)
The goal of this thesis is to design a 3D printer type delta. To describe 3D printing technologies used by this printer, basic printer features and commercially available material used at the print and its comparison. To define all hardware components, which are necessary for construction of the 3D printer type delta. To create a proposal and construct an expansion board to which all hardware components of the printer will be connected. To optimize the print space heating and cooling of the printout. To extend the 3D printer with a Web server, which will ensure the network printing possibility.
357

Nástroj pro 3D rekonstrukci z dat z více typů senzorů / Scalable Multisensor 3D Reconstruction Framework

Šolony, Marek January 2017 (has links)
Realistické 3D modely prostředí jsou užitečné v mnoha oborech, od inspekce přírodních struktur nebo budov, navigace robotů a tvorby map až po filmový průmysl při zaměřování scény nebo pro integraci speciálních efektů. Je běžné při snímání takové scény použít různých typů senzorů, jako například monokulární, stereoskopické nebo sférické kamery nebo 360° laserové skenery, pro dosažení velkého pokrytí scény. Výhoda laserových skenerů a sférických kamer spočívá právě v zachycení celého okolí jako jeden celistvý snímek. Použitím konvenčních monokulárních kamer lze naproti tomu snadno pokrýt zastíněné části scény nebo zachytit detaily. Proces 3D rekonstrukce sestává ze tří kroků: snímání, zpracování dat a registrace a zpřesnění rekonstrukce. Přínos této disertační práce je podrobná analýza metod registrace obrazu ze sférických a planárních kamer a implementace unifikovaného systému sensorů a měření pro 3D rekonstrukci, jež umožňuje rekonstrukci ze všech dostupných dat. Hlavní výhodou navržené unifikované reprezentace je, že umožňuje společně optimalizovat všechny pózy sensorů a bodů scény aplikací nelineárních optimalizačních metod. Tím dosahuje lepší přesnosti rekonstrukce aniž by se výrazně zvýšily výpočetní nároky.
358

Reconstruction of 3D scenes from pairs of uncalibrated images. Creation of an interactive system for extracting 3D data points and investigation of automatic techniques for generating dense 3D data maps from pairs of uncalibrated images for remote sensing applications.

Alkhadour, Wissam M. January 2010 (has links)
Much research effort has been devoted to producing algorithms that contribute directly or indirectly to the extraction of 3D information from a wide variety of types of scenes and conditions of image capture. The research work presented in this thesis is aimed at three distinct applications in this area: interactively extracting 3D points from a pair of uncalibrated images in a flexible way; finding corresponding points automatically in high resolution images, particularly those of archaeological scenes captured from a freely moving light aircraft; and improving a correlation approach to dense disparity mapping leading to 3D surface reconstructions. The fundamental concepts required to describe the principles of stereo vision, the camera models, and the epipolar geometry described by the fundamental matrix are introduced, followed by a detailed literature review of existing methods. An interactive system for viewing a scene via a monochrome or colour anaglyph is presented which allows the user to choose the level of compromise between amount of colour and ghosting perceived by controlling colour saturation, and to choose the depth plane of interest. An improved method of extracting 3D coordinates from disparity values when there is significant error is presented. Interactive methods, while very flexible, require significant effort from the user finding and fusing corresponding points and the thesis continues by presenting several variants of existing scale invariant feature transform methods to automatically find correspondences in uncalibrated high resolution aerial images with improved speed and memory requirements. In addition, a contribution to estimating lens distortion correction by a Levenberg Marquard based method is presented; generating data strings for straight lines which are essential input for estimating lens distortion correction. The remainder of the thesis presents correlation based methods for generating dense disparity maps based on single and multiple image rectifications using sets of automatically found correspondences and demonstrates improvements obtained using the latter method. Some example views of point clouds for 3D surfaces produced from pairs of uncalibrated images using the methods presented in the thesis are included. / Al-Baath University / The appendices files and images are not available online.
359

Fast and Scalable Structure-from-Motion for High-precision Mobile Augmented Reality Systems

Bae, Hyojoon 24 April 2014 (has links)
A key problem in mobile computing is providing people access to necessary cyber-information associated with their surrounding physical objects. Mobile augmented reality is one of the emerging techniques that address this key problem by allowing users to see the cyber-information associated with real-world physical objects by overlaying that cyber-information on the physical objects's imagery. As a consequence, many mobile augmented reality approaches have been proposed to identify and visualize relevant cyber-information on users' mobile devices by intelligently interpreting users' positions and orientations in 3D and their associated surroundings. However, existing approaches for mobile augmented reality primarily rely on Radio Frequency (RF) based location tracking technologies (e.g., Global Positioning Systems or Wireless Local Area Networks), which typically do not provide sufficient precision in RF-denied areas or require additional hardware and custom mobile devices. To remove the dependency on external location tracking technologies, this dissertation presents a new vision-based context-aware approach for mobile augmented reality that allows users to query and access semantically-rich 3D cyber-information related to real-world physical objects and see it precisely overlaid on top of imagery of the associated physical objects. The approach does not require any RF-based location tracking modules, external hardware attachments on the mobile devices, and/or optical/fiducial markers for localizing a user's position. Rather, the user's 3D location and orientation are automatically and purely derived by comparing images from the user's mobile device to a 3D point cloud model generated from a set of pre-collected photographs. A further challenge of mobile augmented reality is creating 3D cyber-information and associating it with real-world physical objects, especially using the limited 2D user interfaces in standard mobile devices. To address this challenge, this research provides a new image-based 3D cyber-physical content authoring method designed specifically for the limited screen sizes and capabilities of commodity mobile devices. This new approach does not only provide a method for creating 3D cyber-information with standard mobile devices, but also provides an automatic association of user-driven cyber-information with real-world physical objects in 3D. Finally, a key challenge of scalability for mobile augmented reality is addressed in this dissertation. In general, mobile augmented reality is required to work regardless of users' location and environment, in terms of physical scale, such as size of objects, and in terms of cyber-information scale, such as total number of cyber-information entities associated with physical objects. However, many existing approaches for mobile augmented reality have mainly tested their approaches on limited real-world use-cases and have challenges in scaling their approaches. By designing fast direct 2D-to-3D matching algorithms for localization, as well as applying caching scheme, the proposed research consistently supports near real-time localization and information association regardless of users' location, size of physical objects, and number of cyber-physical information items. To realize all of these research objectives, five research methods are developed and validated: 1) Hybrid 4-Dimensional Augmented Reality (HD4AR), 2) Plane transformation based 3D cyber-physical content authoring from a single 2D image, 3) Cached k-d tree generation for fast direct 2D-to-3D matching, 4) double-stage matching algorithm with a single indexed k-d tree, and 5) K-means Clustering of 3D physical models with geo-information. After discussing each solution with technical details, the perceived benefits and limitations of the research are discussed with validation results. / Ph. D.
360

High-Speed, Large Depth-of-Field and Automated Microscopic 3D Imaging

Liming Chen (18419367) 22 April 2024 (has links)
<p dir="ltr">Over the last few decades, three-dimensional (3D) optical imaging and sensing techniques have attracted much attention from both academia and industries. Owing to its capability of gathering more information than conventional 2D imaging, it has been successfully adopted in many applications on the macro scale which ranges from sub-meters to meters such as entertainment, commercial electronics, manufacturing, and construction. For example, the iPhone “FaceID” sensor is used for facial recognition, and the Microsoft Kinect is used to track body motion in video games. With recent advances in many technical fields, such as semiconductor packaging, additive manufacturing, and micro-robots, there is an increasing need for microscopic 3D imaging, and several techniques including interferometry, confocal microscopy, focus variation, and structured light have been developed and adopted in these industries. Among these techniques, the structured light 3D imaging technique is considered one of the most promising techniques for in-situ metrology, owing to its advantage of simple configuration and high measurement speed. However, several challenges must be addressed in employing the structured-light 3D imaging technique in these fields.</p><p dir="ltr">The first challenge is the limited measurement range caused by the limited depth of field (DOF). Given the necessity for large magnification in the microscopic structured light system, the DOF becomes notably shallow, especially when pin-hole lenses are adopted. This issue is exacerbated by the fact that the measured objects in the aforementioned industries could contain miniaturized features spanning a broad height range. To address this problem, we introduce the idea of the focus stacking technique, wherein the focused pixels gathered from various focus settings are merged to form an all-in-focus image, into the structured-light 3D imaging. We further developed a computational framework that utilizes the phase information and fringe contrast of the projected fringe patterns to mitigate the influence of object textures.</p><p dir="ltr">The second challenge is the 3D imaging speed. The 3D measurement speed is a crucial factor for in-situ applications. We improved the large DOF 3D imaging speed by reducing the required fringe images from two aspects: 1) We developed a calibration method for multifocus pin-hole mode, which can eliminate the necessity of the 2D image alignment. The conventional method based on circle patterns will be affected during the feature extraction process by the significant camera defocusing. In contrast, our proposed method is more robust since it uses virtual features extracted from a reconstructed white flat surface under a pre-calibrated focus setting. 2)We developed a phase unwrapping method with the assistance of the electrically tunable lens (ETL), which is an optical component we used to capture fringe images under various focus settings. The proposed phase unwrapping method leverages the focal plane position of each focus setting to estimate a rough depth map for the geometric-constraint phase unwrapping algorithm. By doing this, the method eliminates the limitation on the effective working depth range and becomes feasible in large DOF 3D imaging.</p><h4>Even with all previous methodologies, the efficiency of large DOF 3D imaging is still not high enough under certain circumstances. One of the major reasons is that we can still only use a series of pre-defined focus settings to run the focus stacking, since we have no prior on the measured objects. This issue could lead to low measurement efficiency when the depth range of the measured objects does not cover the whole enlarged DOF. To improve the performance of the system under such situations, we developed a method that introduces another computational imaging technique: the focal sweep technique, to help determine the optimal focus settings adapting to different measured objects.</h4><h4>In summary, this dissertation contributed to high-speed, large depth-of-field, and automated 3D imaging, which can be used in micro-scale applications from the following aspects: (1) enlarging the DOF of the microscopic 3D imaging using the focus stacking technique; (2) developing methods to improve the speed of large DOF microscopic 3D imaging; and (3) developing a method to improve the efficiency of the focus stacking under certain circumstances. These contributions can potentially enable the structured-light 3D imaging technique to be an alternative 3D microscopy approach for many academic studies and industry applications.</h4><p></p>

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